Semi trucks have air brakes, no hydraulics some very old trucks had air over hydraulic systems but they used no more pressure than any other system
To change the primary brake system on a C-17, the hydraulic systems utilized are primarily the Utility Hydraulic System and the Brake Pressure Control System. The Utility system provides hydraulic pressure necessary for brake operation, while the Brake Pressure Control System manages the distribution of that pressure to the brakes. Additionally, the Auxiliary Hydraulic System may be engaged for backup functionality. Proper procedures must be followed to ensure safety and effectiveness during the brake system change.
In a closed hydraulic brake system, hydraulic pressure is generated when the brake pedal is pressed, forcing brake fluid through the system. This pressure is transmitted equally throughout the fluid, allowing it to actuate the brake calipers or wheel cylinders at each wheel. The design ensures that even a small force applied at the pedal results in a significant braking force at the wheels, enhancing braking efficiency and control. The system remains sealed to prevent fluid loss and maintain consistent pressure.
Pressure is released from the hydraulic system and brake pistons relax.
the brake control valve is used to control the amount of hydrauic pressure form the hydraulic system to the brake system through the metering valve.
The main difference between a mechanical brake system and a hydraulic brake system is the way they transmit force to stop a vehicle. In a mechanical brake system, force is applied to the brakes through a cable or linkage, while in a hydraulic brake system, force is transmitted through a fluid-filled system using hydraulic pressure. Hydraulic brakes are generally more efficient and provide better braking performance compared to mechanical brakes.
Hydraulic pressure in a brake system is created when the brake pedal is pressed, causing brake fluid to be compressed. This pressure is transmitted through the brake lines to the brake calipers or wheel cylinders, which then apply force to the brake pads or shoes, ultimately slowing down or stopping the vehicle. The higher the hydraulic pressure, the more force is applied to the brakes, resulting in better braking performance and shorter stopping distances.
hydraulic brake system calculations
A typical hydraulic brake system consists of several main components: the master cylinder, which generates hydraulic pressure when the brake pedal is pressed; brake lines that transport the brake fluid; wheel cylinders or brake calipers that apply force to the brake pads or shoes; and the brake pads or shoes themselves, which create friction against the brake rotor or drum to slow or stop the vehicle. Additionally, the system includes brake fluid, which transmits the pressure throughout the system, and various seals and hoses to ensure proper function and prevent leaks.
Converting a mechanical brake system to a hydraulic brake system involves replacing the mechanical components with hydraulic ones. This includes installing a master cylinder, brake lines, calipers, and possibly a new brake pedal. The hydraulic system uses fluid pressure to apply the brakes, providing smoother and more efficient braking compared to mechanical systems. It is important to ensure that all components are compatible and properly installed for safe and effective braking performance.
Newer cars have a Power Brake Booster (or Power Disc Brake system). This system adds hydraulic pressure to the brake system, so when you push the brake pedal, it increases the pressure on the brake pads with hydraulic power. When the car is off, you loose the additional power provided by this hydraulic system. The brakes still work, you just need to push harder. Typically after the engine cuts off, the first time you press the brake it is somewhat normal (hydraulic pressure still in the system) but after that, the pedal becomes harder to press. It is the same concept with Power Steering - you have hydraulic assistance with the engine on, but none with it off (turn the key on without the engine on and turn the wheel - it is possible, just hard).
automatic hydraulic control system
Possible reasons for hydraulic disc brakes to have no pressure could include air in the brake lines, a leak in the system, worn brake pads, or a malfunctioning master cylinder.